In-Situ Growth of Broussonetia-Like NiCo₂O₄ on Carbon Cloth with Tailored Aqueous Capacitance

Tailored broussonetia-like NiCo₂O₄ is grown on carbon cloth using tri-sodium citrate assisted hydrothermal method. The chelating effect of citric ions has been utilized to investigate the morphological and structural evolution of NiCo₂O₄ on carbon cloth, which have been illustrated by scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectra. The results demonstrate that the morphological alteration of NiCo₂O₄ from single nanowire to broussonetia-like structure has been detected after the addition of tri-sodium citrate. Citric ion plays a crucial role as an electrostatic stabilizer in determining this unique structure. When used as binder-free electrode in aqueous supercapacitors, the broussonetia-like NiCo₂O₄ electrode exhibits a specific capacitance of 527.9 F g^-1 at a current density of 0.5 A g^-1. Additionally, an asymmetric supercapacitor is further assembled using NiCo₂O₄ as the positive electrode and activated carbon as negative electrode. The device exhibits a maximum energy of 26.4 Wh kg^-1 at power density of 800 W kg^-1. A long-term cycling stability with 82% capacitance retention is maintained after 20,000 cycles at a current density of 5 A g^-1, indicating the practical applicability of the tested device.